1. Field of the Invention
The present invention relates generally to fiber optic mechanical splice connectors with sequential splice and strain relief, and more specifically, to a mechanical splice connector in which optical fiber splicing and optical fiber strain relief are performed sequentially utilizing a single, multiple-position actuator, or utilizing multiple actuators.
2. Technical Background
A key objective contributing to the proper function of a fiber optic mechanical splice connector is the alignment of the mating optical fibers within the connector. Alignment is typically accomplished by applying a biasing force to a splice component to accurately align the stub optical fiber of the connector with the mating field optical fiber. Conventional mechanical splice connectors typically include a pair of opposed splice components, wherein at least one of the splice components defines a recess, channel or groove for receiving and seating the bare glass portions of the optical fibers. The stub optical fiber and the field optical fiber are aligned and retained between the opposing splice components as the splice components are biased together by an actuator. The splice components are typically disposed within a connector housing, and generally within a ferrule holder secured to the rear of a connector ferrule mounted upon the stub optical fiber. A projection, such as a rib or keel, extends outwardly from one of the splice components through a passageway in the ferrule holder. The actuator, for example a cam member having an internal geometry defining a cam surface, is positioned over the splice components. In an unactuated (also referred to as “un-cammed” or “open”) position, a larger internal diameter of the cam surface is located adjacent the projection with only minimal or no interference with the splice component. As the cam member is moved to the actuated (also referred to as “cammed” or “closed”) position, a smaller internal diameter of the cam surface engages and exerts a radial compressive force on the projection, thus biasing the splice components together and thereby aligning and retaining the stub optical fiber and the field optical fiber between the splice components.
Once the optical fibers are aligned and retained in optical continuity between the splice components, the field optical fiber is typically strain relieved to the rear of the connector. Strain relief is generally accomplished by crimping a lead-in tube or an annular crimp ring about the buffered portion of the field optical fiber. As used herein, the terms “buffered” and “buffered optical fiber” each refer to both tight-buffered optical fiber and jacketed, or loose-tube, optical fiber cable having an outer diameter greater than about 250 microns. In contrast, the terms “un-buffered,” “coated” and “coated optical fiber” each refer to the optical fiber as formed in a standard extrusion manufacturing process, including the core, the cladding and an extruded coating having an outer diameter up to and including about 250 microns. A 250 micron diameter un-buffered (hereinafter “coated”) optical fiber is typically upsized to a 900 micron diameter buffered optical fiber or cable for mechanical strain relief and strength purposes. A drawback to the conventional strain relief technique for mechanical splice connectors is that once the field optical fiber is strain relieved, the splice cannot be reversed and reworked without destroying the connector assembly and potentially damaging the field optical fiber or the connector. United States Patent Application No. 2005/0036744 to Caveny et al. published on Feb. 17, 2005, discloses a stub fiber connector having a reversible actuator disposed about a ferrule holder for reversibly and nondestructively terminating (i.e., splicing) a stub optical fiber and a field optical fiber, while simultaneously providing reversible and nondestructive strain relief to the terminated field optical fiber. The actuator engages a projection (e.g., a rib or keel) protruding through the ferule holder as described above to bias the splice components together. At the same time, a rearward portion of the actuator applies a biasing force to a buffer clamp to engage the buffered portion of the field optical fiber. As a result, the field optical fiber is simultaneously terminated and strain relieved to the connector. The actuator can be reversed to simultaneously release the buffer clamp from the buffered portion of the field optical fiber and the biasing force on the splice components, thereby permitting the field optical fiber to be removed from the connector or repositioned relative to the stub optical fiber.
Although seemingly advantageous, it is not always desirable to simultaneously terminate and strain relieve a field optical fiber to a mechanical splice connector. In particular, it is often preferable to determine the optical continuity of the splice coupling between the stub optical fiber and the field optical fiber prior to strain relieving the field optical fiber so as to avoid potentially damaging the field optical fiber or the connector in the event that the continuity of the optical splice is unacceptable and must be reworked. Further, if the optical splice is unacceptable, additional time and labor must be expended to first reverse the strain relief before removing or repositioning the field optical fiber and again terminating and strain relieving the field optical fiber to the connector. At the same time, it is often desirable for the field optical fiber to be at least partially strain relieved to the connector, and thereby restrained from torsion and localized bending during final assembly of the mechanical splice connector. For example, during final assembly the buffered portion of the field optical fiber may be additionally strain relieved to the connector housing, and a flexible boot or cable guide may be installed on the connector over the field optical fiber immediately adjacent the rear of the connector to prevent the field optical fiber from exceeding its minimum bend radius.
Accordingly, to overcome the disadvantages described above, while preserving certain of the advantages of known mechanical splice connectors, it is desirable in this instance to provide a mechanical splice connector in which optical fiber splicing and optical fiber strain relief are performed sequentially, and in which the field optical fiber is at least partially strain relieved to the connector during final assembly of the connector onto the field optical fiber. In addition to aligning and retaining the bare glass portions of the stub optical fiber and the field optical fiber, it would also be desirable for the mechanical splice connector to be configured to provide strain relief on a coated portion of the field optical fiber having a diameter up to and including about 250 microns, or in the alternative, on a buffered portion of the field optical fiber having a diameter greater than about 250 microns and up to about 900 microns or more. Furthermore, the mechanical splice connector may include a single, multiple-position actuator, wherein the actuator is moved from an unactuated position to a first actuated position to perform optical splicing (referred to herein as “splice actuation”), and then further moved from the first actuated position to a second actuated position to perform strain relief (referred to herein as “strain relief actuation”). Accordingly, the first actuated position is also referred to as the “splice actuation position” and the second actuated position is also referred to as the “strain relief actuation position.” Alternatively, the mechanical splice connector may include multiple actuators, wherein a first actuator is moved from an unactuated position to a first actuated position for splice actuation, and a second actuator is subsequently moved from an unactuated position to a second actuated position for strain relief actuation. Such a mechanical splice connector would permit the optical continuity of the splice coupling to be determined prior to strain relieving the field optical fiber to the connector, thereby providing reversible splice actuation without potentially damaging the field optical fiber or the connector. At the same time, such a mechanical splice connector would insure that the field optical fiber is at least partially strain relieved to the connector, and thereby restrained from torsion and localized bending during final assembly of the mechanical splice connector.